Technical Field
The present invention relates generally to the field of oil lubricated common rail diesel pumps. More particularly, but not exclusively, the present invention concerns an improved drivetrain assembly for an oil lubricated common rail diesel pump.
Description of the Related Art
The components of a common rail fuel injection system include a rail, a high pressure pump and fuel injectors. Radial, unit and in-line pumps are often used in such common rail fuel injection systems.
Unit pumps (UP) can be mounted on a cambox or directly within the engine. There is a current focus on the development of high pressure unit pump designs to achieve higher efficiency of the fuel injection system and to facilitate accurate rail pressure control.
The majority of common rail diesel fuel unit pumps are lubricated using diesel fuel. In cases where high quality diesel fuel is utilised, fuel lubrication is satisfactory. However, in circumstances where poor quality diesel fuels are used for lubrication, for example in some countries of the world, lubrication is unsatisfactory, which impacts on pump performance and longevity.
Oil lubricated common rail diesel pumps are therefore, preferred since lubricity is not compromised as it can be using fuels. In addition, oil lubrication enables the pump to support higher loads and increased pumping forces at higher pressures.
However, oil lubrication can present its own challenges. In particular, where a pump housing becomes full of oil, this can result in large irregular pressure pulses at high pumping speeds. Pressure pulses of the magnitude observed in round tappet oil-lubricated housings can damage front driveshaft seals and can also result in oil being forced into the fuel circuit (past the pumping plunger) having a negative impact on the engine performance.
It is an object of the present invention to address one or more of the problems of the prior art as discussed herein or otherwise.
It is now desired to provide an improved arrangement for an oil lubricated drivetrain arrangement to drive an oil lubricated common rail diesel pump.